Blender 2.81/2.80: How can I change the color of light of a spot - nodes seem to have no effect?
Works the same for me in 2.8 &amp; 2.81-


So the answer is: in the light panel. Where my screen-grab shows the blue colour swatch, just under the type-of-light buttons.

I'm guessing you chose 'use nodes' for the light with Cycles as the renderer, if you notice my screen shot does not have the option in the light panel (as I'm using Eevee).
I had to chose 'use nodes' with cycles as the renderer before switching to eevee.
So the nodes should, by rights, disappear / become ghosted or whatever when you switch to eevee, but obviously do not... Somewhat annoying / confusing!

Help menu / report a bug (or a 'paper-cut' or whatever!)